Genetic variation of theompAand 16S rRNA genes ofRiemerella anatipestifer

The genetic diversity of the 16S rRNA and ompA genes of Riemerella anatipestifer was investigated. A 16S rRNA gene-based PCR was able to amplify all 18 Taiwanese strains and 10 reference strains. The identity of 16S rRNA sequence of these strains and seven other sequences retrieved from GenBank was 95.0-100.0%. The percentage identity of the ompA sequence of the 15 Taiwanese strains and eight reference strains amplified in this study and two other sequences retrieved from GenBank was 88.1-100.0%. Phylogenetic analysis based on the 16S rRNA gene showed that all the R. anatipestifer strains fell into a single cluster. It is concluded that the 16S rRNA gene-based PCR is suitable for the screening of R. anatipestifer infections. Phylogenetic analysis of the ompA of R. anatipestifer resulted in three different clusters, while seven clusters were found when the derived amino acid sequence was the basis of analysis. No apparent cluster was found using the criteria of host, isolate serotype, the year or location of isolation.

Genetic variation of viral protein 1 genes of field strains of waterfowl parvoviruses and their attenuated derivatives

To understand the genetic variations between the field strains of waterfowl parvoviruses and their attenuated derivatives, we analyzed the complete nucleotide sequences of the viral protein 1 (VP1) genes of nine field strains and two vaccine strains of waterfowl parvoviruses. Sequence comparison of the VP1 proteins showed that these viruses could be divided into goose parvovirus (GPV) related and Muscovy duck parvovirus (MDPV) related groups. The amino acid difference between GPV- and MDPV-related groups ranged from 13.1% to 15.8%, and the most variable region resided in the N terminus of VP2. The vaccine strains of GPV and MDPV exhibited only 1.2% and 0.3% difference in amino acid when compared with their parental field strains, and most of these differences resided in residues 497-575 of VP1, suggesting that these residues might be important for the attenuation of GPV and MDPV. When the GPV strains isolated in 1982 (the strain 82-0308) and in 2001 (the strain 01-1001) were compared, only 0.3% difference in amino acid was found, while MDPV strains isolated in 1990 (the strain 90-0219) and 1997 (the strain 97-0104) showed only 0.4% difference in amino acid. The result indicates that the genome of waterfowl parvovirus had remained highly stable in the field.

Epidural analgesia associated with a fatal outcome in a patient with an unrecognized brain tumour

A fatality associated with epidural analgesia in a patient with an unsuspected brain tumour has not been reported in the literature. We describe a case of postoperative lumbar epidural analgesia in a 54-year-old female patient who had an undiagnosed brain tumour and a fatal outcome postoperatively. The factors that potentially contributed to this mishap and the possible alternative management of this patient are discussed.

The Prevalence and Antimicrobial Susceptibilities of Salmonella and Campylobacter in Ducks in Taiwan

Cloacal swabs were sampled from 100 duck farms in Taiwan between March 2000 and January 2001 for isolation and standard cultivation of Salmonella spp. and thermophilic Campylobacter spp. Salmonella spp. were isolated from 4.6% (91/2000) of ducks from 20% (20/100) of duck farms. Ten serotypes of Salmonella enterica were identified: S. Potsdam (31.9% of isolates), S. Dusseldorf (18.7%), S. Indiana (14.3%), S. Typhimurium (7.7%), S. Hadar (5.5%), S. Newport (4.4%), S. Derby (4.4%), S. Montevideo (2.2%), S. Schwarzengrund (2.2%), and S. Asinnine (1.1%). Isolation of S. Asinnine or S. Indiana from poultry had not hitherto been described in Taiwan. The salmonella isolation rate in ducklings under two weeks of age was significantly higher than the other age groups (P<0.05). Campylobacter spp. were isolated from 43.5% (1045/2400) of ducks from 92% (92/100) of duck farms. Among them, 991 isolates (94.8%) were identified as C. jejuni and 54 isolates (5.2%) as C. coli. The campylobacter isolation rate in ducklings under two weeks of age was significantly lower than other age groups (P<0.05). Antimicrobial susceptibility testing was conducted by the disk diffusion and E- test methods. The results indicated that Salmonella isolates were 100% susceptible to amikacin, amoxicillin/clavulanic acid, ceftraxone, cephalothin, ciprofloxacin, norfloxacin, ofloxacin, and polymyxin B. A markedly higher antimicrobial resistance to amoxicillin, florfenicol, flumequine, josamicin/trimethoprim, nalidixic acid, nitrofurantoin, norfloxacin, ofloxacin, polymyxin B, sulfamethoxazole/trimethoprim and tetracycline was found in campylobacter isolates.

Antigenic and genotypical characterization of Newcastle disease viruses isolated in Taiwan between 1969 and 1996

Three major epidemics of Newcastle disease (ND) occurred in Taiwan over the past three decades (in 1969, 1984, and 1995). In order to gain a better understanding of the relationships between past ND epizootics in Taiwan, 36 ND viruses (NDVs) isolated between 1969 and 1996 were characterized antigenically and genotypically. The antigenicity of these viruses was analysed by their ability to cause binding of mouse monoclonal antibodies (mAbs) to cell cultures infected with the isolate. Using a panel of 22 mAbs to divide NDVs into subgroups, a total of 18 binding patterns were revealed. The sequences covering the cleavage site of the fusion protein gene of these isolates were also determined. The results of the phylogenetic analysis placed 36 NDVs into I, II, VIb, VIIa, VIII and two novel genotypes (provisionally termed X and VIh). The 1969 velogenic isolates were of genotypes X and VIh; the 1984-1985 velogenic isolates were genotyped VIb, VIh, VIIa, and X; while the 1995-1996 velogenic isolates were genotyped VIIa or VIII. Some 1969 and 1984 velogenic isolates were of the same mAbs binding pattern and genotype, and the mAbs binding patterns of the 1995-1996 isolates have not been seen before. It is concluded that velogenic NDVs of different genotype and antigenic type have co-circulated in Taiwan at least since 1969. Also there were epizootiological links between strains isolated in 1969 and 1984, whereas the 1995-1996 epidemic was caused by new antigenic variants.

Reversal of mivacurium chloride: edrophonium of spontaneous recovery in microscopic laryngeal surgery

BACKGROUND

A double-blind, randomized study was designed to compare the recovery manner of mivacurium infusion with or without edrophonium reversal in microscopic laryngeal surgery. Neuromuscular blockade was quantified using the train-of-four stimuli to the ulnar nerve and quantification of the ratio of the fourth twitch to the first twitch.

METHODS

With the approval of the Human Studies Committee of the Taipei Veterans General Hospital and patient informed consent, 40 healthy (ASA I or II) patients with age from 24 to 54 years, undergoing microscopic laryngeal surgery were randomly selected for study. Mivacurium chloride 0.2 mg/kg was given intravenously, and then it was given in continuous infusion to maintain muscle relaxation at 90% twitch block during the procedure. At the end of operation, mivacurium infusion was terminated. In a double-blind manner, group I patients (n = 20) received intravenous edrophonium 1 mg/kg and atropine 0.01 mg/kg for reversal when T1 was at 10% recovery whereas patients in Group II (n = 20) received placebo in the same manner. Mean infusion rate, recovery index (RI50, time from T1 25% to T1 50%; RI75, time from T1 25% to T1 75%), extubation time, and discharge time between groups were compared. Nausea, vomiting, and dysrhythmias were also documented until the patient was discharged from hospital.

RESULTS

The demographic data between two groups were similar. The recovery index (RI75) for group I was shorter than that of placebo group (5.3 +/- 2.19 min vs. 7.3 +/- 0.9 min) and the difference was statistically significant (P = 0.017). There were no statistically significant differences in mean infusion rate, incidence of nausea and vomiting, and discharge time from the POR. The incidence of tachycardia or arrhythmia in group I was significantly greater than that in group placebo.

CONCLUSIONS

Mivacurium, a short-acting nondepolarizing agent, is a suitable muscle relaxant for patients receiving microscopic laryngeal surgery. Recovery time with the use of edrophonium as reversal agent was shorter than with placebo, but extubation and discharge time did not differ in two groups. The time which could be saved by the use of edrophonium for reversal of mivacurium to hasten the maximal recovery appears to be less than a few minutes. Therefore, clinically, the value of routine use of edrophonium to obtain a faster recovery does not outweigh its demerits of cost and risk and is not worthy of recommendation.

Retina-specific cis-elements and binding nuclear proteins of carp rhodopsin gene

The upstream cis-elements controlling the retina-specific expression of carp rhodopsin gene were fully characterized in vivo. Transgenic studies demonstrated that both carp neural retina leucine zipper response-like element (cNRE, within nucleotides (nt) -63 to -75) and carp-specific element (CSE, nt -46 to -52) were crucial to reporter gene expression in medaka retinae. The retina-specific expression rates of embryos injected with nt -1 to -641 and longer fragments were much higher than those of embryos injected with nt -1 to -138 and shorter fragments, indicating that an enhancer is located in the nt -138 to -641 region. Retinal extracts and the probe BAT-1 (nt -90 to -120) formed two DNA-protein complexes, B1 and B2. Retinal extracts and the probes cNRE and CSE formed the complexes N1 and C1, respectively. The protein factors in B1 and C1 were mammal-like cone-rod homeobox proteins.

Age-related maculopathy: an expanded genome-wide scan with evidence of susceptibility loci within the 1q31 and 17q25 regions

PURPOSE

We seek to identify genetic loci that contribute to age-related maculopathy susceptibility.

METHODS

Families consisting of at least two siblings affected by age-related maculopathy were ascertained using eye care records and fundus photographs. Additional family members were used to increase the power to detect linkage. Microsatellite genotyping was conducted by the National Heart, Lung and Blood Institute Mammalian Genotyping Service and the National Institutes of Health Center for Inherited Disease Research. Linkage analyses were conducted with parametric (autosomal dominant; heterogeneity lod score) and nonparametric methods (S(all) statistic) using three diagnostic models. False-positive rates were determined from simulations using actual pedigrees and genotyping data.

RESULTS

Under our least stringent diagnostic model, model C, 860 affected individuals from 391 families (452 sib pairs) were genotyped. Sixty-five percent of the affected individuals had evidence of exudative disease. Four regions, 1q31, 9p13, 10q26, and 17q25, showed multipoint heterogeneity lod scores or S(all) scores of 2.0 or greater (under at least one model). Under our most stringent diagnostic model, model A, the 1q31 heterogeneity lod score was 2.46 between D1S1660 and D1S1647. Under model C, the 17q25 heterogeneity lod score at D17S928 was 3.16. Using a threshold of 1.5, additional loci on chromosomes 2 and 12 were identified.

CONCLUSIONS

The locus on chromosome 1q31 independently confirms a report by Klein and associates mapping an age-related maculopathy susceptibility gene to this region. Simulations indicate that the 1q31 and 17q25 loci are unlikely to be false positives. There was no evidence that other known macular or retinal dystrophy candidate gene regions are major contributors to the genetics of age-related maculopathy.

Uniform GFP-expression in transgenic medaka (Oryzias latipes) at the F0 generation

A green fluorescent protein (GFP) cDNA flanked by inverted terminal repeats (ITR) of adeno-associated virus was constructed. The construct sharply improved the efficiency and specificity of the transient expression of genes driven by two general promoters (cytomegalovirus and medaka beta-actin) and one muscle-specific promoter (zebrafish alpha-actin) in transgenic medaka. In addition, treatment with ITR sequence-containing constructs resulted in a dramatic increase in the number of embryos showing uniform GFP-expression at F0. Of the GFP-positive embryos, 34.6% (81/234), 10% (10/60), and 18% (38/212) showed homogenous GFP-expression for the derivative constructs of the cytomegalovirus, alpha-actin, and beta-actin promoters, respectively. As a result of uniform GFP-expression, green fluorescence in founders was (a) extended for an entire lifetime without degradation, and (b) transmitted as a genetic trait to F1 and F2 progeny of some transgenic lines via Mendelian inheritance. A Southern blot analysis revealed a random integration of the transgene into the genome of founders and progeny in both head-to-tail and tail-to-tail concatemerization patterns. Interestingly, some transgenic medaka with uniform and strong fluorescence could be visually noticeable to the unaided eye.

Enhanced expression and stable transmission of transgenes flanked by inverted terminal repeats from adeno-associated virus in zebrafish

Mosaic expression of transgenes in the F0 generation severely hinders the study of transient expression in transgenic fish. To avoid mosaicism, enhanced green fluorescent protein (EGFP) gene cassettes were constructed and introduced into one-celled zebrafish embryos. These EGFP gene cassettes were flanked by inverted terminal repeats (ITRs) from adeno-associated virus (AAV) and driven by zebrafish alpha-actin (palpha-actin-EGFP-ITR) or medaka beta-actin promoters (pbeta-actin-EGFP-ITR). EGFP was expressed specifically and uniformly in the skeletal muscle of 56% +/- 8% of the palpha-actin-EGFP-ITR-injected survivors and in the entire body of 1.3% +/- 0.8% of the pbeta-actin-EGFP-ITR-injected survivors. Uniform transient expression never occurred in zebrafish embryos injected with EGFP genes that were not flanked by AAV-ITRs. In the F0 generation, uniformly distributed EGFP could mimic the stable expression in transgenic lines early in development. We established five transgenic lines derived from palpha-actin-EGFP-ITR-injected embryos crossed with wild-type fish and 11 transgenic lines derived from pbeta-actin-EGFP-ITR-injected embryos crossed with wild-type fish. None of these transgenic lines failed to express the transgene, a result confirmed by polymerase chain reaction analysis. Stable mendelian transmission of the transgenes was achieved in both alpha-actin and beta-actin transgenic lines without changing the patterns of expression and integration. Progeny inheritance test and Southern blot analysis results strongly suggest that transgenes flanked by AAV-ITRs were integrated randomly into the genome at a single locus with a concatamerized multiplier. Thus, incorporating AAV-ITRs into transgenes results in uniform gene expression in the F0 generation and stable transmission of transgenes in zebrafish.

Molecular structure, dynamic expression, and promoter analysis of zebrafish (Danio rerio) myf-5 gene

We isolated a 1,438 bp cDNA fragment that encoded Myf-5 myogenic factor of zebrafish. The deduced amino acid contained 237 residues, including the basic helix-loop-helix domain that is conserved in all known Myf-5. The zebrafish myf-5 transcripts were first detectable at 7.5 hpf, increased substantially until 16 hpf, and then declined gradually to an undetectable level by 26 hpf. During somitogenesis, zebrafish myf-5 transcripts were distributed mainly in the somites and segmental plates. Prominent signals occurred transiently in adaxial cells in two parallel rows but did not extend beyond the positive-signal somites. Various lengths of upstream region of zebrafish myf-5 fused with EGFP gene were used to carry out transgenic analysis. Results showed that a small, 82 bp (nucleotide positions from -82 to -1), regulatory cassette is sufficient to control the somite- and stage-specific expression of zebrafish myf-5 during early development.

Introducing foreign DNA into tiger shrimp (Penaeus monodon) by electroporation

Electroporation was used to introduce pFLAG-CMV-1-BAP, a DNA fragment that includes a bacterial alkaline phosphatase gene driven by a human cytomegalovirus (CMV) promoter, into Penaeus monodon zygotes. The transgenic tiger shrimp was achievedby using 10kV, 28 pulses, 120 g sec pulse time, 10 cycles, and a DNA concentration of 37.5 microg/mL. The hatching rate of electroporated zygotes (46%) was significantly lower than that of zygotes in the untreated group (89%). The survival rate of postlarvae in the electroporated group using a DNA concentration of 37.5 microg/mL decreased from 0.6% for postlarva 45 to 0.4% for postlarva 120. Based on dot blot analysis, the rate of gene transfer was 37% in mysis-stage, 23% postlarva 15(PL15), 19% postlarva 45(PL45), and 21% 4-month-old (about PL120). Genomic Southern blotting demonstrated that DNA from transgenic tiger shrimp contained fragments of exogenous DNA that were smaller, larger and of the same molecular size as pFLAG-CMV-1-BAP. Transferred DNA fragments were integrated into the genomes of 31% of the transgenic tiger shrimp. The exogenous DNA was mosaically distributed in a wide variety of tissues. Immunohistochemical staining revealed that the FLAG-BAP fused-protein encoded by pFLAG-CMV-1-BAP was present in the ovaries of some transgenic tiger shrimp.

Muscle regulatory factor gene: zebrafish (Danio rerio) myogenin cDNA

Myogenin is one of the basic helix-loop-helix proteins that regulate muscle-specific gene expression. Using reverse transciption-polymerase chain reaction (RT-PCR), 5'- and 3'-rapid amplification of cDNA ends (RACE), zebrafish myogenin cDNA was cloned from mRNA of embryos at 10-96 h post-fertilization. The cDNA, at 1384 base pairs (bp), contained a 771-bp open reading frame with 113- and 500-bp flanking regions at the 5'- and 3'-ends, respectively. The deduced amino acid sequences of zebrafish myogenin encoded a 256-amino-acid polypeptide. In a comparison with myogenin of carp, trout, Xenopus, chicken and human, zebrafish myogenin shared 90.9, 77.6, 70.3, 62.9 and 51.5% amino acid identity, respectively. The basic helix-loop-helix domains in myogenin are all conserved. The molecular phylogenic tree demonstrated that myogenin of zebrafish is more closely related to that of fish than to the myogenin of other vertebrates.

Transfer of foreign gene to giant freshwater prawn (Macrobrachium rosenbergii) by spermatophore-microinjection

We developed a spermatophore-microinjection (SMI) technique that allows exogenous DNA fragments to be transferred easily into the giant freshwater prawn (Macrobrachium rosenbergii), an important aquacultural shellfish and aquatic invertebrate model. From 28 to 1, 000 ng of the circular plasmid pGL, in a total volume of 1 microl, were directly microinjected into spermatophores. Fertilization and hatching of prawns created with SMI were completed in vivo. Fertilization and hatching rates in the SMI treatments did not differ from those of the untreated control group. The genomes of free swimming, SMI-created larvae (21 days after fertilization) were analyzed using PCR and Southern blot analyses. A product with a molecular mass of 680 bp was amplified. It corresponded to amplifications of pGL, and Southern blot analysis revealed that the amplified band was positive. The gene transfer rate was primarily dependent on the concentration of DNA during SMI. The higher the concentration of pGL, the higher the rate of gene transfer. PCR and Southern blot analyses detected the existence of foreign DNA in 16 of 23 samples (70%) of genomic DNA isolated from hatched larvae in the 750 ng pGL SMI treatment. SMI, described here for the first time, is the simplest and most efficient method for mass producing transgenic giant freshwater prawns.

Electroporated sperm mediation of a gene transfer system for finfish and shellfish

We investigated gene transfer in finfish and shellfish via electroporated sperm. The mobility of sperm, the fertilization rate, the hatching rate, gene transfer rate, and abnormality rate of derived embryos were primarily dependent on the voltage level and concentration of DNA during electroporation. Optimal conditions for sperm of each species of aquatic animals can be reached. Genome of the electroporated sperm was analyzed by PCR, and it was shown that an expected-sized product was amplified, corresponding to that of the transgene's amplification. Southern blotting also showed that a positive band located at the same position as the DNA fragment used for the transfer was found in the electroporated sperm after DNase treatment. When the genome isolated from embryos, larvae, juvenile, and adult individuals, all derived from sperm electroporated with foreign DNA molecules, was analyzed by PCR, the existence of foreign DNA was detected in some samples. The integration of the transferred DNA into the genome of transgenic samples was also shown by Southern blot analysis. There was a mosaic distribution of exogenous DNA in a wide variety of tissues analyzed. In addition to CAT activity being positive for the experimental larvae, the transferred GH gene was functional in transgenic finfish and shellfish and resulted in fast-growing transgenic varieties. The overall evidence strongly suggests that the use of electroporated sperm is the simplest yet most efficient approach to perform mass gene transfer in aquacultural animals, including marine mollusks.

Structural characterization and transcriptional pattern of two types of carp rhodopsin gene

This work characterizes the genomic structures of two types of carp (Cyprinus carpio) rhodopsin (cRh) gene, i.e. type I (cRh-I) and type II (cRh-II). Two types of cRh gene share only 45.6% polynucleotide identity in the upstream region from nucleotide -3436 to +97. However, three conserved regions are found. Homologies to the consensus recognition sites for transcription factors, Crx and Nrl, which are involved in photoreceptor-specific expression, are also observed in cRh genes. With specific polymerase chain reaction (PCR) primers, the two types of cRh gene can be clearly discriminated from each carp genome. Most carps exhibit both types of cRh gene, however, there are still carps possessing either cRh-I or cRh-II. Both cRh-I and cRh-II mRNAs are expressed at an approximately equal level in both eyes extracted from a carp carrying both types of cRh gene.

Two distinct c-ski cDNAs of fish, tilapia (Oreochromis aurea)

Two classes of tilapia c-ski cDNA (accession nos. AJ012011, AJ012012), designated as tski1 and tski2, respectively encoded a 687 and a 714 AA protein and shared a 57% AA identity. Comparison with the Ski proteins of chickens, humans and Xenopus, tilapia TSki polypeptides shared a 60, 57, and 57% (TSki1) and 67, 63, and 61% (TSki2) AA identity, respectively. The most and the least abundant c-ski mRNAs are located in the brain and the skeletal muscle, respectively. Both tski1 and tski2 were widely expressed in the adult tissues examined, but tski2 transcripts were at higher levels except in the ovary and oocytes: tski1 transcripts were predominant in the ovary, whereas tski2 transcripts were predominant in the testes. In the oocytes, the tski1 mRNA was a maternally-inherited stockpile that subsequently was degraded, so that the expression ratio of tski1 to tski2 transcripts declined gradually as the fish developed from oocyte to 4-cm fry. Mol. Reprod. Dev. 54:223- 231.

Functional organization and evolution of mammalian hexokinases: mutations that caused the loss of catalytic activity in N-terminal halves of type I and type III isozymes

Mammalian hexokinases are believed to have evolved from a 100-kDa hexokinase which itself is a product of duplication and fusion of an ancestral gene encoding a 50-kDa glucose 6-phosphate-sensitive hexokinase. Type II hexokinase has been shown to possess two distinct functional active sites, one in each half, which functionally resemble the original 100-kDa hexokinase, whereas type I and III isozymes possess only one active site in the C-terminal halves. This study was conducted to identify which mutations caused the loss of catalytic activity in the N-terminal halves of type I and III isozymes. Arg 174 and Ser 447 in type I isozyme and Asp 244 in type III isozyme are speculated to be the cause, because they reside adjacent to the "catalytic" site and corresponding residues, Gly 174, Asp 447, and Gly 231, are conserved in the N-terminal half of type II isozyme as well as all other 50-kDa units that possess catalytic activity. Mutations G174R and D447S in the N-terminal half of type II isozyme reduced specific activity by approximately 79 and 57%, respectively. Therefore, neither mutation alone can account for the inactivation of the N-terminal active site in type I isozyme. Either mutation, G174R or D447S, had moderate effects on Michaelis constants, K(m), for glucose and ATP. Mg(2+). Intriguingly, mutation D447S introduced a novel inhibition by unchelated ATP (K(i) = 68 microM ATP, competitive vs ATP. Mg(2+)) to the N-terminal active site of type II isozyme. Mutation G231D caused instability to type II hexokinase and near complete loss of catalytic activity (95%), suggesting that mutation G231D not only hinders catalysis at the N-terminal active site but also leads to structural instability in type II hexokinase.

Effects of choline and other nicotinic agonists on the tectum of juvenile and adult Xenopus frogs: a patch-clamp study

We have used anatomical methods and whole-cell patch-clamp recording to assess the distribution of nicotinic receptors in the tectum of Xenopus frogs and to measure effects of nicotinic ligands (carbachol, cytisine and nicotine) on glutamatergic spontaneous miniature excitatory postsynaptic currents. Our results confirm that retinotectal axons account for the majority of nicotinic receptors in the tectum and that nicotinic agonists exert presynaptic effects that increase the rate of transmitter release on to tectal cells. The nicotinic blockers mecamylamine and methyllycaconitine reduced responses to carbachol and cytisine. A small percentage of cells also showed postsynaptic responses. We have assessed whether there are developmental changes in the frequency of occurrence of spontaneous miniature excitatory postsynaptic currents. The first three months post-metamorphosis fall within the critical period for the dramatic plasticity displayed by binocular inputs during development in Xenopus. During this period, visual activity governs the formation of orderly maps relayed from the ipsilateral eye via the cholinergic projection from the nucleus isthmi to the tectum. In this study, we have found that critical-period tecta (two to 12 weeks postmetamorphosis) tend to have higher spontaneous activity than do older tecta (two to 69 weeks postmetamorphosis), and that nicotinic agonists increase that activity in both groups, with the result that the peak rates in response to nicotinic agonists are higher during the critical period than later. We also investigated the possible role of choline as an agonist of nicotinic receptors in the tectum. We have found that choline, as well as carbachol and cytisine, can cause a reversible increase in the rate of miniature excitatory postsynaptic currents. This result may help to explain how the isthmotectal projection, which accounts for the overwhelming majority of cholinergic input to the tectum, can exert effects on retinotectal terminals even though there are no morphologically identifiable synapses between the two populations. We have examined the morphology of cells filled with biocytin during the patch-clamp experiments, and we find that cells with dendrites in the stratum zonale, a layer with particularly dense input from the contralateral nucleus isthmi, have higher spontaneous activity than cells with dendrites that do not extend into that layer. Nicotinic agonists increased the activity recorded in both classes of cells. In addition, four pretectal cells were identified. Nicotinic agonists increased the rate of spontaneous activity recorded in that population. The results indicate that retinotectal transmission in the superior colliculus can be increased presynaptically by activity of the cholinergic projections of the nucleus isthmi. This modulation may be the basis for observations that blocking of cholinergic input disrupts the formation of topographic retinotectal projections. Moreover, the ability of choline to activate these receptors suggests that this metabolite of acetylcholine may permit paracrine activation of presynaptic receptors even though the tectum contains high acetylcholinesterase activity.

Benzophenones as xanthine oxidase inhibitors

Eight synthetic benzophenones were tested for their inhibitory effects on xanthine oxidase (XO). The enzyme, XO catalyses the oxidation of hypoxanthine to xanthine and of xanthine to uric acid, which has a lambda max of 295 nm, forming the basis for a spectrophotometric assay for the activity of XO. The results showed that 2,2',4,4'-tetrahydroxybenzophenone (6), 3,4,5,2',3',4'-hexahydroxybenzophenone (8) and 4,4'-dihydroxybenzophenone (3) displayed the inhibitory effects on XO with an order of activity of IC50 = 47.59, 69.40 and 82.94 microM, respectively. The apparent inhibition constants (Ki) of (8) and (3) were 15.61 and 64.86 microM respectively, and both of them induced mixed type (non-competitive-uncompetitive) inhibitions of the substrate xanthine.

Epizootic of Chlamydia psittaci infection in goats in Taiwan

Epizootic abortion in goats has been frequently reported in Taiwan since 1993. The outbroken flocks were found in most of districts in Taiwan. No apparent clinical signs were found in aborted doe. The typical abortion occurred in the last two months of pregnancy. The incidence of abortion was from 10% to 87% in outbroken farms in 1993, and a total of 976 out of 2130 pregnancies (46%) were found abortion in our investigation. Gross lesions in aborted fetuses included generalized haemorrhage and swollen liver. Chlamydia psittaci was isolated from tissues of aborted fetuses and from vaginal swabs of aborted does. Chlamydial antibodies were detected among 67% to 100% of aborted does from epizootic flocks. The C. psittaci was diagnosed as the causal agent in enzootic abortion. This is the first report on chlamydial isolation and antibody surveys in epizootic abortion in goats in Taiwan.

Optimization of the solubilization and renaturation of fish growth hormone produced by Escherichia coli

Growth hormone (GH) enhances the growth rate of aquacultured fish and shellfish, but it is difficult to extract native GH from fish pituitary glands. However, fish recombinant GH (rGH) can be efficiently synthesized by Escherichia coli cells, although it exists in denatured form in inclusion bodies (IB). We studied the solubilization of IB and the renaturation of rGH to help facilitate the production of a large amount of biologically active rGH. A 100-ml sample of rGH-producing E. coli produced 73.43 +/- 5.47 mg IB (dry weight, n = 3) after 20 h induction by 1 mM isopropyl beta-o-thiogalactopyranoside. Interestingly, if the bacteria were induced by 0.1 mM beta-lactose, 95.3 +/- 3.43 mg of IB was obtained. The optimal conditions for denaturation and renaturation of rGH were when IB were solubilized in 6 M guanidine hydrochloride and then dialysed against pH 10 dialysis buffer (50 mM ammonium bicarbonate and 2 mM EDTA) containing 100 mM L-arginine, 2 mM oxidized glutathione and 2 mM reduced glutathione for 24 h at 4 degrees C in a volume ratio of 3 to 500. At least 20% of the denaturated rGH in IB was renatured. Juvenile black sea bream injected with 0.05 microgram/g resultant rGH once every 2 weeks exhibited significant increases (P < 0.05) in weight gain (84%) relative to fish in the control group over a 16-week period. This process is an economical and effective way to obtain an active form of rGH biosynthesized by a prokaryotic system.

A second type of rod opsin cDNA from the common carp (Cyprinus carpio)

A second type of rhodopsin cDNA from carp (cRh-II) shared 97.2% polynucleotide identity with the previously reported cRh-I. The deduced amino acid sequences of cRh-I and cRh-II exhibited 98.6% identity. The key difference between these two types of cRh is that valine at position 169 of cRh-I was replaced by glutamic acid in cRh-II. Southern blot analysis of genomic DNA showed that there were two types of cRh gene. These two rod opsin genes were proven to be expressed in carp retinas by using RT-PCR with type-specific primers.

Functional organization of mammalian hexokinases: characterization of the rat type III isozyme and its chimeric forms, constructed with the N- and C-terminal halves of the type I and type II isozymes

Previous studies have shown that catalytic function is associated with both halves of the Type II isozyme of mammalian hexokinase, while the Type I isozyme is functionally differentiated into a catalytic C-terminal half and regulatory N-terminal half. The Type III isozyme has now been shown to be similar to the Type I isozyme in its functional organization. Chimeras composed of the N-terminal half of Type III hexokinase and the C-terminal half of either Type I or Type II hexokinase have activities that can be attributed to the C-terminal half and are similar in activity to chimeras composed of the C-terminal half of Type III and the intrinsically inactive N-terminal domain of Type I or the inactivated (by site-directed mutation) N-terminal half of Type II hexokinase. Virtually no activity was seen with chimeras constructed with the N-terminal half of the Type III isozyme and catalytically inactive (by site-directed mutation) C-terminal halves of Type I or Type II hexokinase. Substrate inhibition by Glc is seen only with the Type III isozyme and with chimeric forms containing the C-terminal half of Type III hexokinase and the N-terminal half of Type I or Type II isozyme, the latter inactivated by site-directed mutation; this is attributed to conformational changes induced by binding of Glc to a low affinity site in the N-terminal half, with subsequent effect on catalytic activity of the C-terminal half. These results also provide further insight into the role of interactions (or lack of interactions) between the N- and C-terminal halves in the inhibition of the Type I-III isozymes by Glc-6-P, its antagonism by low concentrations of Pi, and the inhibition seen at higher concentrations of Pi.

Sperm as a carrier to introduce an exogenous DNA fragment into the oocyte of Japanese abalone (Haliotis divorsicolor suportexta)

We investigated gene transfer in abalone via electroporated sperm. The mobility of sperm electroporated either in seawater or in marine invertebrate physiological solution was as good as that of the control group. The fertilization rate reached as high as 94.7-99.6% (93.0-99.7% for the control group) when 200 eggs were fertilized by 10(6) or 10(7) sperm treated with electroporation at 10 kV and 2(7) pulses for six cycles. Moreover, the fertilization rate of sperm electroporated in the presence of foreign DNA (opAFP-2000CAT) ranging from 0.1 to 3.2 micrograms and at voltages ranging from 2 to 10 kV, at 2(7) or 2(11) pulses for six or 12 cycles showed no differences from the control sperm. After DNase digestion, the genome of the electroporated sperm was analysed by polymerase chain reaction, and it was shown that a 138-bp product was amplified, corresponding to the transgene's amplification product. Southern blotting also showed that a positive band located at the same position as that of opAFP-2000CAT was found in the electroporated sperm after DNase treatment. Analysis by PCR of the genome isolated from a trochophore-stage abalone larva, derived from sperm electroporated with 3.2 micrograms opAFP-2000CAT, showed the existence of foreign DNA in 13 out of 20 examined samples (65%). The integration of the transferred DNA into the genome of transgenic abalone was also shown by Southern blot analysis. Furthermore, CAT activity was positive for the experimental larvae, but the level of CAT expression was lower than that of larvae derived from sperm electroporated with pCAT-Control vector, driven by SV40 promoter and enhancer sequences. These results demonstrate the potential for the use of sperm as mass gene transfer strategy in marine mollusks such as abalone.

Carp cDNA sequence encoding a putative diazepam-binding inhibitor/endozepine/acyl-CoA-binding protein

A full-length cDNA coding for common carp diazepam-binding inhibitor (DBI)/endozepine (EP)/acyl-CoA-binding protein (ACBP) was isolated and sequenced. The deduced DBI/EP/ACBP is comprised of 87 amino acids (including initiating methionine) without possessing a signal peptide. Common carp DBI/EP/ACBP displays 77%, 78%, 70%, 63%, 61% and 45% identity with human, bovine, rat, frog, duck and yeast DBI/EP/ACBP, respectively.

Functional organization of mammalian hexokinases: both N- and C-terminal halves of the rat type II isozyme possess catalytic sites

Previous work has shown that catalytic function is associated exclusively with the C-terminal half of the Type I isozyme of mammalian hexokinase. In contrast, we now demonstrate that both halves of the Type II isozyme possess comparable catalytic activities. Mutation of a catalytically important Ser residue to Ala at analogous positions in either the N- or the C-terminal halves (S155A or S603A, respectively) of the rat Type II isozyme resulted in approximately 60% reduction in specific activity of the enzyme, with more than 90% reduction in the doubly mutated enzyme (S155A/S603A). Catalytic activity was retained in a chimeric hexokinase comprising the N-terminal half of Type II hexokinase and catalytically inactive (by site-directed mutation) C-terminal half of the Type I isozyme. The N- and C-terminal catalytic sites of Type II hexokinase are similar in V(max) and K(m) (approximately equal to 130 microM) for glucose; however, the N-terminal site has a lower (0.45 vs 1.1 mM) K(m) for ATP, is slightly more sensitive to inhibition by the product analog 1,5-anhydroglucitol-6-P, and is much more sensitive to inhibition by P(i). It is suggested that the Type II isozyme most closely resembles the 100-kDa hexokinase which resulted from duplication and fusion of a gene encoding an ancestral 50-kDa hexokinase and which was the precursor for the contemporary Type I, Type II, and Type III mammalian isozymes. Subsequent evolutionary changes could then have led to functional differentiation of the N- and C-terminal halves, as seen with the Type I (and possibly the Type III) isozyme.

Highly efficient expression of fish growth hormone by Escherichia coli cells

A PCR product encoding the mature segment of fish pregrowth hormone (pre-GH) was inserted into an Escherichia coli expression vector, pET, in which the ori site was replaced by that of pUC19. The yield of recombinant GH (rGH) was as high as 44 to 47% of total protein. This rGH was immunoreactive to GH antibody. After renaturation, rGH was used to inject fish with 0.1 microgram of rGH per g once every 2 weeks, and this resulted in increases in weight (65%), percent weight gain (165%), and length (22%) relative to those of an untreated control group at week 16 and onward.

Initiation of the transgenic lacZ gene expression in medaka (Oryzias latipes) embryos

In total, 4165 medaka (Oryzias latipes) oocytes were injected with three DNA constructs separately, and results showed that exogenous lacZ expression was transient and stage-dependent. The initiation of the transgene expression was at the mid-blastula stage for embryos derived from oocytes injected with pmiwZ, containing the long terminal repeat (LTR) of the Rous sarcoma virus, and with pCAGGS-lacZ, containing the enhancer and promoter of the immediate early gene of the human cytomegalovirus, respectively, whereas embryos derived from oocytes injected with pMoZtk, containing the LTR of the Moloney murine leukemia virus, started expression at the late-blastula stage. These reveal that the earliest onset of the exogenous lacZ gene should be by the mid-blastula stage. Therefore the mid-blastula transition phenomenon in embryogenesis known in other animal species exists in medaka embryos.

Functional organization of mammalian hexokinases: characterization of chimeric hexokinases constructed from the N- and C-terminal domains of the rat type I and type II isozymes

Chimeric hexokinases consisting of either the N-terminal half of Type I hexokinase fused with the C-terminal half of the Type II isozyme (NICII) or the inverse pair (NIICI), along with the parental isozymes, were expressed in COS-1 cells. The thermal stability of the chimeras was intermediate between that of the highly labile Type II isozyme and the relatively stable Type I hexokinase. In their Kms for substrates, Glc and ATP, the chimeric enzymes were similar to the parental isozyme from which the C-terminal half was derived. Although the Type I and Type II isozymes were similar in their sensitivity to inhibition (competitive vs ATP) by the Glc-6-P analogs, 1,5-anhydroglucitol 6-phosphate (AnGlc-6-P), and Glc-1,6-bisphosphate, the chimeric enzymes differed markedly, with the NIICI chimera being much more sensitive and the NICII chimera much less sensitive than either parental form to these inhibitors. In contrast, the response of the chimeras to Pi, either as an antagonist of inhibition by AnGlc-6-P or, at higher concentrations, as an inhibitor, was correlated with the origin of the N-terminal domain. The results are consistent with the view that catalytic function is associated with the C-terminal domain of the Type I isozyme, with regulatory function--inhibition by Glc-6-P and its analogs and antagonism of this inhibition by Pi--being mediated by the N-terminal domain.

Molecular cloning of the common carp (Cyprinus carpio) rhodopsin cDNA

A recombinant phage clone containing a 1584 nucleotides rhodopsin cDNA was screened from a carp retinal cDNA library. The inserted DNA consisting of a single open reading frame of 1062 nucleotides at positions 72 to 1133 encodes a 354 amino acid polypeptide. The deduced amino acid sequence of carp rhodopsin showed 95.7, 85.5 and 74.4% identity with that of goldfish, sand goby and lamprey, respectively. The sites of palmitoylation, glycosylation, disulfide bond formation and Schiff base formation in the putative rhodopsin are all conserved.

Genetic analysis of antibody responses of turkeys to Newcastle disease virus and Pasteurella multocida vaccines

Heritability (h2) of 16-wk BW and primary and secondary antibody responses and genetic and phenotypic correlations among these traits were estimated for 931 male and female turkeys vaccinated with Newcastle disease virus (NDV) and Pasteurella multocida. Turkeys from a line selected for 22 or 23 generations for increased 16-wk BW were vaccinated at 6 and 12 wk of age with blood samples collected 3 wk postvaccination. Antibody titers were determined using an ELISA method and transformed to log(e) for analysis. Heritability estimates for primary and secondary antibody responses to NDV were .380 +/- .070 (SE) and .296 +/- .063, respectively. For primary and secondary antibody responses to P. multocida, h2 estimates were .458 +/- .075 and .333 +/- .066, respectively. Heritability estimate for 16-wk BW was .404 +/- .071. The genetic correlation between primary and secondary antibody responses to NDV was .491 +/- .150. There was no genetic correlation between primary and secondary antibody responses to P. multocida. Although the genetic correlation between primary antibody responses to NDV and P. multocida was .292 +/- .159, the genetic correlation between secondary responses to the two antigens did not differ from zero. There were no genetic correlations between antibody responses and 16-wk BW. Similar results were observed for phenotypic correlations. Based on heritability and genetic correlation estimates, it would be possible to improve antibody responses to either NDV or P. multocida singularly; however, to improve antibody responses to both antigens, selection would have to be applied for each antigen.

Effect of genetic selection for increased body weight and sex of poult on antibody response of turkeys to Newcastle disease virus and Pasteurella multocida vaccines

Primary and secondary antibody responses of 671 turkeys of two genetic lines to Newcastle disease virus (NDV) and Pasteurella multocida vaccines were examined. The randombred control line (RBC2) and a subline (F) of RBC2 had been selected for increased 16-week body weight. Poults were vaccinated at 6 and 12 weeks of age, and serum samples were collected 3 weeks after each vaccination. Antibody titers were determined using an enzyme-linked immunosorbent assay. Line F turkeys had significantly higher 9-week and 15-week serum antibody titers to NDV than line RBC2. However, line RBC2 had significantly higher serum antibody titers to P. multocida at 15 weeks of age than line F. The 9-week and 15-week serum antibody titers to NDV were significantly higher in females than males, but males had significantly higher 15-week serum antibody titers to P. multocida than females. Sex of poults did not contribute significantly to variation in serum antibody response to P. multocida at 9 weeks of age.

Studies on antigenic relatedness of classic and variant strains of infectious bursal disease viruses

Antigenic relatedness of six classic and variant strains of serotype 1 infectious bursal disease virus (IBDV) and one serotype 2 IBDV was investigated by Western blotting and enzyme-linked immunosorbent assay (ELISA) using polyclonal, monoclonal, and monospecific antibodies to single viral proteins (VP2 and VP3). All virus strains cross-reacted similarly, and the viruses were not distinguishable from each other by ELISA or Western blot analysis performed with polyclonal or non-neutralizing monoclonal and monospecific antibodies. Non-neutralizing antibodies against the VP2 (40 kilodaltons) reacted strongly with VP2 of classic and variant strains of serotype 1 and reacted weakly with VP2 of serotype 2 OH strain. This indicated that common antigens were recognized and that these epitopes were not strictly dependent on the native structure of the virus.

Infectious bill atrophy syndrome caused by parvovirus in a co-outbreak with duck viral hepatitis in ducklings in Taiwan

In October 1989, an epizootic duckling disease with high mortality occurred in Taiwan. The disease was characterized by droopiness, inappetence, ataxia, ruffled feathers, and watery diarrhea. Affected ducklings were lame, were unable to stand, showed opisthotonos, and often died 3 or 4 days after the onset of the disease. Tolerant maturing ducklings displayed atrophic upper bills with a protruding tongue and became stunted as they reached maturity. No diagnostic histopathologic lesions were found in these ducklings. Fourteen parvovirus isolates, 33 duck viral hepatitis virus (DVHV) isolates, two adenovirus isolates, and two reovirus isolates were obtained and identified from more than 500 sick ducklings in the epizootic. The epizootic was diagnosed as a co-outbreak of duck parvovirus infections and duck viral hepatitis. The high mortality in ducklings and the bill atrophy syndrome were reproduced in ducklings by inoculating the parvovirus isolates alone. The epizootic was controlled by an emergency immunization program of ducklings with sera collected from recovered ducks or a bivalent inactivated vaccine composed of local DVHV and parvovirus isolates.

Molecular cloning and expression of yellowfin porgy (Acanthopagrus latus houttuyn) growth hormone cDNA

1. The growth hormone cDNA of yellowfin porgy (ypGH cDNA) consisted of 915 base pairs. 2. The deduced amino acid (aa) sequence showed that the pre-GH comprised 204 residues, of which the first 17 residues formed a signal peptide. 3. Comparison of aa sequence of ypGH to seabream, tuna, rainbow trout and chum salmon showed that ypGH shared 95.1, 94.1, 65.3 and 62.4% homology with these species, respectively. 4. By expressing the ypGH cDNA in E. coli, a polypeptide around 23 kilodaltons (kDa) was found which was immunoreactive to GH antibody.

Genetic variation in resistance of turkeys to experimental infection with Newcastle disease virus

Seven hundred eighty male and female turkeys representing four genetic lines were challenged in four experiments with the Texas GB strain of Newcastle disease virus (NDV). The lines of turkeys included two randombred control lines (RBC1 and RBC2), a subline (E) of RBC1 selected for increased egg production, and a subline (F) of RBC2 selected for increased 16-week body weight. Mortality in turkeys of subline F (32.5%) was significantly higher than that in turkeys of line RBC2 (15.8%), subline E (17.5%), and line RBC1 (18.4%). At the end of each experiment, surviving birds were tested for antibody to NDV using the enzyme-linked immunosorbent assay (ELISA) and hemagglutination-inhibition (HI) test. Turkeys of subline E and line RBC1 had significantly lower ELISA antibody titers than those of subline F and line RBC2. Subline F had the highest HI antibody titers, followed in decreasing order by lines RBC2 and RBC1 and subline E. No apparent correlation was found between antibody response and mortality after NDV challenge.

Effect of cell-culture passage on the pathogenicity and immunogenicity of two variant strains of infectious bursal disease virus

Two variant strains of infectious bursal disease virus, IN and E, were adapted and passaged in an established cell line (BGM-70) 30 times and 40 times, respectively. Passage in cell culture resulted in loss of pathogenicity. However, both viruses maintained their antigenicity and immunogenicity, as demonstrated by the immunofluorescence and virus-neutralization tests and by the satisfactory protection induced by vaccinating specific-pathogen-free (SPF) chickens with inactivated preparations of both passaged viruses. No protection was induced when the passaged viruses were given to SPF chickens as live vaccines. It is speculated that the passaged viruses might have lost some ability to replicate in their natural host, resulting in lack of protection.

Glucocorticoid and mineralocorticoid receptor-binding characteristics in obese (ob/ob) mice

Adrenalectomy prevents development of obesity in genetically obese (ob/ob) mice. Replacement studies have shown that these mice exhibit hypersensitivity to corticosterone. This study was conducted to determine if this increased sensitivity was associated with alterations in corticoid receptor number or binding affinity. Cytosolic glucocorticoid receptor numbers were lower by 26% in liver, 23% in brain, and 26% in brown adipose tissue of 8-wk-old male ob/ob mice when compared with lean mice. Cytosolic glucocorticoid receptor numbers were similar in liver and brain of 4-wk-old lean and ob/ob mice is likely secondary to elevated plasma corticosterone concentrations in these older mice. Adrenalectomy increased cytosolic glucocorticoid receptor numbers in liver and brain of 8-wk-old ob/ob mice to values comparable to those in lean mice. Injection of dexamethasone (0.5 or 5 micrograms/g body wt) equally lowered cytosolic glucocorticoid receptor numbers in liver and brain of adrenalectomized ob/ob and lean mice. Brain mineralocorticoid receptor numbers and response to dexamethasone were similar in ob/ob and lean mice. These results suggest that the site responsible for increased sensitivity of ob/ob mice to corticosterone is postreceptor binding.

Detection of antibodies against Bordetella avium in turkeys by avidin-biotin enhancement of the enzyme-linked immunosorbent assay and the dot-immunobinding assay

An avidin-biotin-enhanced enzyme-linked immunosorbent assay (AB-ELISA) and an avidin-biotin-enhanced dot-immunobinding (AB-DIB) assay for detecting antibody to Bordetella avium in turkey sera were developed and compared with the microagglutination (MA) test. Whole-cell antigen, biotin-labeled goat anti-turkey IgG conjugate, and horseradish-peroxidase-labeled streptavidin were used in the AB-ELISA and AB-DIB assay. The AB-ELISA and AB-DIB assay were sensitive, specific, and reproducible. These assays were superior to the MA test for measuring acquired and maternal antibodies against B. avium. All MA-positive sera were positive by two assays, but some sera negative by MA test had titers in the AB-ELISA and AB-DIB assay. AB-ELISA and AB-DIB titers showed a positive correlation (r = 0.866), and AB-ELISA was more sensitive than the AB-DIB assay.

Neuronal motion after-response induced in the tectal neurons of toads by moving textured background

When an object is held stationary in the center of the receptive field of a tectal neuron in a toad and a textured background is moved for a period of time, some neurons produce a burst of discharges immediately after the movement of the background ceases. This effect was first found in a recent study and temporarily called 'neuronal motion after-response'. A total of 66 tectal neurons in toads were examined, and 29 out of them showed the effect. In the different neurons under investigation, the firing rate varied from a few spikes to discharges of very long duration. The appearance of the motion after-response was independent of either the object/background contrast (i.e. black against white vs. white against black) or the direction of the background movement. In order to induce this effect, however, the object must be of sufficient size, and the background must be moved for a sufficient length of time. For most tectal neurons, an 8 x 8 degree square was large enough to induce the motion after-response, but for several others, the size of the object had to be similar to that of the excitatory receptive field of the neuron. The duration of the background movement was also crucial: at least 20 s of background movement was necessary for the motion after-response to occur.

Red cell distribution width in the detection of iron deficiency in maintenance hemodialysis patients

Iron deficiency is a frequent complication in maintenance hemodialysis patients. Red cell distribution width (RDW) was recently used as an indicator in early detection of iron deficiency. One hundred and thirty nine patients maintained on hemodialysis were studied for the usefulness of RDW in detection of iron deficiency. Serum ferritin less than 30 ug/dl was defined as iron deficiency in these patients. Another 69 patients with iron deficiency not entering hemodialysis were chosen as a control group. The sensitivity of RDW elevation to detect iron deficiency in chronic hemodialysis patients was only 36.7% which was much lower than that of the control group (62.3%). However, it was still more sensitive than microcytosis in the detection of iron deficiency in chronic hemodialysis patients because none of them showed microcytosis. The specificity and positive predictive value of RDW elevation in respect to iron deficiency were 62.4% and 9.6% respectively. This study demonstrated that the use of RDW in the detection of iron deficiency in chronic hemodialysis patients was superior to mean corpuscular volume but still limited.

After-effects of moving textured background in motion-sensitive neurons of anuran optic tectum

Motion-sensitive neurons in anuran optic tectum were shown to respond to a stationary object centered in the excitatory receptive field, if a textured background moved for a while and then stopped ('motion after-response'). This motion after-response was attributed to a post-inhibitory rebound activation derived from effects of masking the excitatory receptive field center surrounded by an antagonistic inhibitory region. It was suggested that a similar rebound activation mechanism may also be involved in a certain type of perceptual motion after-effects in humans.

Evolutionary implications of two rainbow trout growth hormone genes

The primary structures of two rainbow trout growth hormone mRNAs (GH1 and GH2) have been deduced by direct sequencing of their respective cDNA clones and portions of the mRNA. Both GH1 and GH2 mRNA contain open reading frames comprised of 630 nucleotides and encode 210 amino acid residues of which 11 are variant. The translated regions of both mRNA are flanked by a short but rather conserved 5'-end, and a relatively long but highly diverged 3'-end. The differences at translated and 3'-untranslated regions suggest that the GH1 and GH2 mRNA originate from different loci. The GH1 and GH2 mRNA are likely transcribed from two distinct loci which were duplicated during tetraploidization of salmonid genome between 50 to 100 million years ago.The GH2 gene has been isolated and sequenced from a rainbow trout genomic library. This gene spans a region of approximately 4 kilobases. The trout GH gene is comprised of 6 exons and 5 introns, in contrast to 5 exons and 4 introns in mammals. The additional intron in the trout gene interrupts the translated regions that are analogous to the last exon of the mammalian counterpart. The alleged internally repeating sequences in mammalian GH, prolactin (Pr1) and placental lactogen (PL) are not observed in the predicted polypeptide sequence of trout GH. In addition, direct repeats that flank exons I, III and V of mammalian GH, Pr1 and PL genes are absent in trout gene. These findings indicate that the rainbow trout GH gene structure does not support the current hypothesis that internally repeated regions in GH, Pr1 and PL arose from a small primordial gene.

Influence of stationary and moving textured backgrounds on the response of visual neurons in toads (Bufo bufo L.)

Previous studies have shown that configurational prey recognition in common toads is performed by feature-analyzing functional units consisting of assemblies of connected neurons such as retinal (classes R2, R3), tectal [classes T5(1), T5(2), T5(3)], and pretectal (class TH3) cells. In the present paper, effects of textured backgrounds on the response of these neurons to a configurational moving stimulus have been tested quantitatively. (1) In all investigated neurons, neither the overall activation nor the respective stimulus-response relationships were significantly influenced by a stationary black/white-textured background as far as black stimulus objects are concerned. (2) The neuronal activity in response to a moving object (signal) could be inhibited (masked) if a black/white-textured background (noise) was moving simultaneously at the same speed. The strength (I) of this 'surround inhibition' (signal masking by the background) was different in the various classes of neurons, i.e. strongest for T5(2) and weakest for R3: IT5(2) greater than IT5(1) greater than IT5(3) greater than IR2 greater than ITH3 greater than IR3. These inhibitory effects were not correlated with the size of the neuronal excitatory receptive field (ERF), since T4 neurons (ERF = 180 degrees) in this context displayed response properties similar to T5(2) neurons (ERF less than 30 degrees). (3) It is suggested that the signal (prey)-masking effect of a moving textured background is brought about by pretecto (TH3)-tectal [T5(1), T5(2)] inhibitory connectivity which allows toads: (a) to select prey from nonprey; (b) to discriminate between prey and a textured background, and (c) to determine the origin of moving retinal images caused either by object movement or by self-induced motion.

Edge preference of retinal and tectal neurons in common toads (Bufo bufo) in response to worm-like moving stripes: the question of behaviorally relevant 'position indicators'

Previous experiments have shown that during prey-catching behavior (orienting, snapping) in response to a worm-like moving stripe common toads, Bufo bufo (L.) exhibit a contrast- and direction-dependent edge preference. To a black (b) stripe moving against a white (w) background (b/w), they respond (R*) preferably toward the leading (l) rather the trailing (t) edge (Rl* greater than Rt*), thus displaying 'head preference'. If the contrast-direction is reversed (w/b), the stripe's trailing edge is preferred (Rl* less than Rt*), hence showing 'tail preference'. In the present study, neuronal activities of retinal classes R2 and R3 and tectal classes T5(2) and T7 have been extracellularly recorded in response to leading and trailing edges of a 3 degrees X 30 degrees stripe simulating a worm and traversing the centers of their excitatory receptive fields (ERF) horizontally at a constant angular velocity in variable movement direction (temporo-nasal or naso-temporal). The behavioral contrast-direction dependent edge preferences are best resembled by the responses (R) of prey-selective class T5(2) neurons (Rl:Rt = 10:1 for b/w, 0.3:1 for w/b) and T7 neurons (Rl:Rt = 6:1 for b/w, 0.4:1 for w/b); the T7 responses may be dendritic spikes. This property can be traced back to off-responses dominated retinal class R3 neurons (Rl:Rt = 6:1 for b/w, 0.5:1 for w/b), but not to class R2 (Rl:Rt = 1.2:1 for b/w and 0.9:1 for w/b). The respective edge preference phenomena are independent of the direction of movement. When stimuli were moved against a stationary black-white structured background, the 'head preference' to the black stripe and the 'tail preference' to the white stripe were maintained in class R3, T5(2), and T7 neurons. If the stripe traversed the ERF together with the structured background in the same direction at the same velocity, the responses of tectal class T5(2) and T7 neurons were strongly inhibited, particularly in the former. Responses of retinal R2 neurons in comparable situations could be reduced by about 50%, while class R3 neurons responded to both the stimulus and the moving background structure. The results support the concept that the prey feature analyzing system in toads applies principles of (i) 'parallel' and (ii) 'hierarchial' information processing. These are (i) divergence of retinal R3 neuronal output contributes to stimulus edge positioning and (in combination with R2 output) area evaluation in tectal neurons and to stimulus area evaluation and (in combination with R4 output) sensitivity for moving background structures in pretectal neurons.(ABSTRACT TRUNCATED AT 400 WORDS)